ok ill say exactly what i typed in the console:
sleep 6000 &
returned [1] 2733
sleep 6000 &
returned [2] 2734
sleep 6000 &
returned [3] 2735
sleep 6000 &
returned [4] 2736

then i type in jobs and it returned
[1] Running sleep 6000 &
[2] Running sleep 6000 &
[3]- Running sleep 6000 &
[4]+ Running sleep 6000 &

my questions is why does [3] have a - and [4] a +